Puccinia obscura  

Spermogonia amphigenous, minute, in dense roundish clusters, honey-coloured.
Aecia amphigenous and on the petioles, on roundish or irregular yellow spots in loose clusters or scattered, peridium cup-shaped or cylindrical with a torn margin; aeciospores 16-22 µm diam., globose to angular, finely verruculose, yellowish.
Uredinia generally hypophyllous, usually on irregular confluent purplish-brown spots, scattered, elliptical or rectangular in outline, long covered by the epidermis, pulverulent, rusty-yellow. Urediniospores 18-26 (-32) x 15-22 (-30) µm, ellipsoidal to ovoid, the wall rather thick, echinulate ,pale to cinnamon-brown with 2 supra-equatorial pores, spinose when young but often ± smooth below the pores when mature.
Telia similar, but compact, pulvinate, covered or surrounded by the split epidermis, blackish-brown. Teliospores 30-48 x 14-20 µm, broadly ellipsoidal, rounded or rarely truncate or conical above, slightly constricted at the septum, attenuated below, smooth, brown, 4-5 µm thick at the apex, pedicels subhyaline, persistent, to 30p long. Mesospores frequently present.

Description largely adapted from WIlson & Henderson (1964).